When taking chest X-rays it has been the practice of the technologist to cut small pieces from a thin lead sheet and then use adhesive tape so the person being X-rayed can tape the lead pieces over his or her nipples so that, when X-rayed, the nipples will be located on the negative by small white areas since the lead is opaque to X-rays. The purpose of identifying the nipple is so that the doctor examining the negative will not be misled by the otherwise shaded or darkened areas that are sometimes caused by the exposed nipples and thereby result in a misdiagnosis.